A new research study finds that the adverse consequences of low birthweight last into the middle-school years. Despite favorable outcomes for many children in this group, extremely premature babies are at risk for long-term developmental problems.
Most previous studies of children with low birthweight have focused on the early childhood years. This research has documented a wide range of deficits that are greater in children at the lower end of the birthweight spectrum. Problems in attention, academic performance and visual-motor ability are especially prominent.
In the current study, sponsored by the National Institute of Child Health and Human Development, 60 children with very low birthweight (less than two pounds), 55 low birthweight (two to three pounds) and 49 full-term babies were compared at seven and eleven years of age. Lower-birthweight children exhibit more problems in math, academic performance, behavior, and visual-motor function even when IQ is taken into account.
Ten of the 65 children in the lowest weight group had neurosensory impairment (cerebral palsy, vision or hearing loss) at the time of the middle-school-age assessment. Four of the 55 children in the low-birthweight group were also impaired, while none of the full-term children had neurosensory problems.
Lower scores on nearly all measures
On individually administered tests the lowest-birthweight group had lower scores on nearly all measures compared to the other groups. The lower birthweight groups had lower IQ, poorer academic achievement, more behavior problems and hyperactivity, poorer adaptive behavior, more grade retention and higher rates of special-education placement.
Even after controlling for IQ, there were differences between groups on tests of mental processing, visual-motor skill and math performance. The lowest-birthweight group also showed smaller increases in test scores and fewer reductions in behavior problems between seven and eleven years of age compared to children who outweighed them at birth. The only gender differences were found on teachers’ ratings of hyperactivity, which were higher for boys.
Even small variations in weight within groups significantly affected performance. The lower the birthweight, the less favorable the outcomes in each group. Children who were cognitively impaired had lower birthweights than others in their group.
Problems still present at middle school
This study confirms that problems stemming from low birthweight continue to be present at middle-school age. The differences in cognitive ability in extremely-low-birthweight babies are accompanied by differences in academic performance and in parents’ ratings of behavior and attention problems.
Although a significant proportion of children — 37 percent in the very low birthweight group and 62 percent in the low birthweight group — show no signs of impairment at middle school, the rates of impairment in these groups are significantly higher than for full-term children.
Researchers speculate that deficits present when these children started school may have rendered them less able than full-term children to take advantage of learning opportunities.
The fact that 37 percent of children in the lowest birthweight group were free of developmental impairments is remarkable, given their extreme prematurity and multiple neonatal complications. Follow-up of this present sample will continue through their adolescence.
It should be kept in mind that this was a local, not national, sample and that these children were born before the use of more advanced neonatal treatments. These researchers warn, however, that while changes in neonatal practices have increased survival rates, they may not have reduced developmental problems.
“Middle-School-Age Outcomes in Children with Very Low Birthweight”, Child Development Volume 71, Number 6, December 2000, Pp. 1495-1511.
Published in ERN, February 2001, Volume 14, Number 2.